Pete Waterman may have a lot to answer for after introducing Rick Astley, Steps and Jason Donovan to the airwaves, but having seen how he spent some of the proceeds, I'm now prepared to forgive him. Waterman is the kind of friend every middle-aged man should have; a man who has built an extension to accommodate his model railway set. Before last night, I hadn't even realised I was interested in toy trains, let alone suffered from engine envy. But now I feel I could happily while away an evening with Pete, helping to direct his trains round and round in circles.

The Joy of (Train) Sets: The Model Railways Story (BBC4) made no great claims to be anything other than an entertaining film about the male fascination with trains (it is almost exclusively male, despite the appearance of Maggie the Modeller), and how it was indulged by the Fabian WJ Bassett-Lowke for the gentry before the first world war, by Hornby for the middle classes between the wars, and by Triang for the working classes in the 1960s. There was a bit of social history – I realise now that my own father would have been far more likely to have bought me a bigger train set if he had smoked a pipe – but it was chiefly a celebration of futility.

"It's essentially a pointless activity," said Iain Rice, a model railway enthusiast. And how refreshing it was to hear him say it. I'm deeply suspicious of people who insist their interests are morally and educationally superior to everyone else's. Whatever it takes to keep anyone sane – or at least out of trouble – is fine by me. The only slightly jarring note was several modellers talking about how nice it was to see a younger generation, inspired by Thomas the Tank Engine, taking an interest in the hobby, when the only person in the whole film who looked under the age of 50 was the editor of Model Rail Magazine. The whole point of hobbies like this is that they are an exercise in nostalgia; if you're nostalgic in your 20s, you probably do have a problem.

I don't suppose there were many women, or men under 50, who bothered to watch this. Come to think of it, I doubt there were many people watching it at all. But it made me very happy. There's more than enough rubbish on television for every other demographic group, and it makes a change to having something just for me. If Timeshift wants to make documentaries about philately, collecting first edition books and football memorabilia, then I promise I will stay in to watch those too.

Around the time Bassett-Lowke discovered that a whole generation of upper-class men had been slaughtered and that he would need to downsize his model trains for the middle classes, the British Army was beginning to come to terms with the effects of shell shock. Nearly 100 years on, you might be wondering just how much it has learned. Life after War: Haunted by Helmand (BBC3) followed the survivors of 9 Platoon, 2 Rifles, three years after it lost five men in a series of IED attacks on 10 July 2009.

It was hard to watch. The commander, Old Etonian Alex Horsfall, who lost a leg and a hand in the attack and was trying to organise a reunion, was the one giving the best impression of someone who had recovered from the experience. But his empty flat and emptier eyes suggested that he was still spending a lot of time in his own private hell. Of the others, one had committed suicide, several were still experiencing nightmares and post-traumatic stress, one was a borderline alcoholic, another had split up with his partner, and none had reintegrated into civilian life. The army may be a lot better at saving lives on the battlefield these days, but it has still got a lot to learn about piecing minds back together.

Bob Servant Independent (BBC4) began life as a series of books and radio shows about a Dundee burger magnate taking on the world at large, and his first TV outing, in which he is standing as an independent in a local election, suggests he might have done better to stay where he was. Delusional interior worlds are much easier to create – and a lot funnier – when they are done as a series of soundscapes or monologues. Seeing Bob in the flesh diminished him, as it became increasingly difficult to see his extreme vision as absurd, rather than moronic. Still, there were some good moments and Greg McHugh (Howard from Fresh Meat), who played Anders the local radio presenter, is almost worth his own show.

• This article was amended on 24 January 2013 to correct the spelling of Iain Rice's name.